For more than a decade, George Zimmerman dreamed of a life in law enforcement — but instead of becoming a real cop, he lived out his big blue fantasy by tracking down stray dogs, “suspicious” children and other intruders in his gated Florida community.

Before he gunned down unarmed black teenager Trayvon Martin — an incident President Obama confronted Friday, calling it a tragedy — Zimmerman had been a nuisance to 911 operators. He would carry around with him a pistol and the hope that he would one day wear a badge.

Zimmerman grew up in Manassas, Va., a Catholic altar boy who was the son of a military man.

He wrote in his senior yearbook that he was “going to Florida to work with my godfather who just bought a $1 million business” — but Zimmerman’s heart was pulling him toward law enforcement.

“He wanted to join the police force — either the State Police or the county police,” said George Hall, 78, a retired minister and longtime neighbor of Zimmerman in Virginia.

“He asked me to write him a letter of recommendation, and I was glad to. He was such a wonderful kid. I thought he’d be the kind of officer I wanted protecting me.

“I had no doubt about his abilities to look out for citizens. I would have an easier time respecting him than I have with some officers now.”

Hall said he didn’t know when Zimmerman’s detective dreams were dashed.

But that didn’t stop Zimmerman from playing the part.

He had a license to carry a concealed weapon, and he started a neighborhood watch last September in his gated community in Sanford, Fla.

Well before that, he was calling cops for just the slightest, racially tinged suspicions.

As the watch volunteer at the 260-unit Retreat at Twin Lakes, he became a paranoid pest — peppering 911 with at least 46 calls. They varied in urgency, but in the last year focused mostly on black men or boys.

That included a “suspicious” 7- to 9-year-old boy with a “skinny build” and short black hair.

In November 2006, he called to report a red Toyota pickup truck “driving real slow” around the neighborhood for five minutes.

In September 2009, he called about a “yellow speed bike” weaving in and out of traffic and doing “wheelies.”

A month later, Zimmerman was hot on the scent of an “aggressive white and brown pit bull.”

And last August, he reported a black man he believed was “involved in recent” burglaries.

The son of a white father and a Peruvian mother, Zimmerman was ambitious, friends said.

Zimmerman moved to Florida in 2001, and he enrolled in Seminole State College in 2003, pursuing a vocational certificate to become an insurance agent.

Down South, he had his own brushes with the law. In 2005, he was arrested for assaulting a cop and resisting arrest. He avoided conviction by entering a pretrial-diversion program.

That same year, his ex-fiancée, Veronica Zuazo, filed a restraining order against him, claiming he had been near her home “just checking up” on her. When she demanded that he leave, he allegedly grew violent, pushing her, according to the Miami Herald.

The next day, he filed his own petition and claimed she wanted him to stay the night and grew violent when he refused. A judge ordered both to stay away from each other.

In 2008, he explained away his arrest on an enrollment application to a citizen’s law-enforcement academy program at the Seminole County Sheriff’s Office.

“I was in an altercation with an undercover officer that was taking part in an ATF sting for underage drinking in UCF [University of Central Florida],” Zimmerman wrote, according to documents obtained by The Post.

“He never told me he was an officer and assaulted me first.

“My father is a retired magistrate judge for the Supreme Court of Virginia and my mother was a deputy clerk of court for over 20 years,” he wrote. “I hold law-enforcement officers in the highest regard as I hope one day to become one.”

Zimmerman was accepted into the 14-week course, which offers civilians an inside look at the sheriff’s office, the courthouse and the jail. He never became a cop — he was a pencil pusher, according to the Orlando Sentinel.

Zimmerman re-enrolled at Seminole State in 2009 — still with the hopes of joining law enforcement — but was booted last week because of safety concerns for him, the Los Angeles Times said.

Zimmerman’s paranoia led directly to his Feb. 26 encounter with Trayvon Martin, 17.

Police said Zimmerman first spied Trayvon walking from a 7-Eleven at about 7:15 p.m. and called police to report him as suspicious. Although he was told by a 911 operator not to get involved, Zimmerman followed Trayvon.

They scuffled and Zimmerman shot him once in the chest with his licensed Kel-Tec 9mm semiautomatic handgun. Zimmerman says he acted in self-defense. A special prosecutor, the FBI and the US Department of Justice are investigating.

Zimmerman is also facing trouble from the militant New Black Panther Party, which yesterday offered a $10,000 reward for his “capture,” the Sentinel reported.

George Zimmerman has placed at least 46 calls to 911 in the last eight years. In the last year, his calls focused on blacks in his gated community:

April 22, 2011: Reports “black male, 7 to 9 years old with skinny build,” walking around the neighborhood.

Aug. 3, 2011: Calls in a black male he “believes is involved in

recent burglaries in the neighborhood.”

Aug. 6, 2011: Fingers two black teens he thinks “have been burglarizing homes in this area.”

Oct. 1, 2011: Reports two black males, approximately 20 to 30 years old, whom he does not recognize. He says he’s “concerned due to recent burglaries in the area.”

Feb. 2, 2012: Drops dime on a black male because it is “unknown what he is doing.”

Feb. 26: Calls about Trayvon Martin

Hey, we’ve had some break-ins in my neighborhood, and there is a real suspicious guy.